1. Field of the Invention
The present invention relates to a titanium alloy which exhibits high strength in an operating temperature range and is excellent in hot workability because of its small flow stress at high temperatures. The titanium alloy can be widely utilized in the fields of, for example, the aircraft industry, the automobile industry, and the ship industry, taking advantage of its high strength and excellent hot workability.
2. Description of Related Art
α-β type titanium alloys typified by a Ti-6Al-4V alloy are light in weight, and have high strength and excellent corrosion-resistance. For this reason, the alloys have been positively put into practical use as structural materials, shell plates, an the like, serving as alternatives to steel materials in various fields of the aircraft, automobile, and ship industries, and other industries.
However, the high-strength titanium alloys are inferior in forgeability and secondary workability because of the high flow stress in the α-β temperature range, i.e., in the hot working temperature range, which is a large obstacle in pursuing the generalization thereof. For this reason, the number of working steps and the number of heating steps during hot working are increased, so that an enough excess metal is given at the sacrifice of the product yield. Under such conditions, hot working is actually performed. Even when hot press forming is performed, the limit size of the applicable pressing capability is accepted. Further, even when an alloy is hot rolled into a rod form or a linear form, if high-speed rolling is adopted, a large working heat generation occurs due to the large flow stress, which causes structure defects. Therefore, it can not but to roll the alloy at a low speed, which is a large obstacle in enhancing the productivity.